A S treptomyces‐ specific member of the metallophosphatase superfamily contributes to spore dormancy and interaction with A spergillus proliferans

We have identified, cloned and characterized a formerly unknown protein from S treptomyces lividans spores. The deduced protein belongs to a novel member of the metallophosphatase superfamily and contains a phosphatase domain and predicted binding sites for divalent ions. Very close relatives are encoded in the genomic DNA of many different Streptomyces species. As the deduced related homologues diverge from other known phosphatase types, we named the protein M pt S (metallophosphatase type from S treptomyces ). Comparative physiological and biochemical investigations and analyses by fluorescence microscopy of the progenitor strain, designed mutants carrying either a disruption of the mpt S gene or the reintroduced gene as fusion with histidine codons or the egfp gene led to the following results: (i) the mpt S gene is transcribed in the course of aerial mycelia formation. (ii) The M pt S protein is produced during the late stages of growth, (iii) accumulates within spores, (iv) functions as an active enzyme that releases inorganic phosphate from an artificial model substrate, (v) is required for spore dormancy and (vi) M pt S supports the interaction amongst S treptomyces lividans spores with conidia of the fungus A spergillus proliferans . We discuss the possible role(s) of M pt S ‐dependent enzymatic activity and the implications for spore biology.